Forehearth feeder tube lift system

ABSTRACT

A feeder tube assembly for a feeder bowl of a glass melting furnace forehearth. The feeder tube assembly has an horizontally extending elongate support arm, and a feeder tube that is carried by the support arm at a location near an end of the support arm. The feeder tube is rotatable about its longitudinal central axis with respect to the support arm, and the support arm carries drive elements for rotating the feeder tube about its longitudinal central axis. The support arm is supported on a vertically extending servo motor actuated linear actuator, and the elevation of the support arm is adjustable by actuation of the linear actuator, a releasable brake being provided to prevent rotation of the servo motor when it is desired to prevent a change in elevation of the support arm. The position of the support arm relative to the linear actuator is independently adjustable both longitudinally of the support arm and transversely of the support arm, and the support arm is rotatable with respect to the linear actuator when it is desired to replace a feeder tube carried thereby or the feeder bowl directly below it.

FIELD OF THE INVENTION

[0001] This invention relates to a feeder tube assembly for a feederbowl of a glass melting furnace forehearth. More particularly, thisinvention relates to a lift mechanism for adjustably supporting aforehearth feeder tube during its operating, and for lifting the feedertube from its operating position during the removal of the feeder tubefor replacement of the feeder tube or replacement of the feeder bowl.

BACKGROUND OF THE INVENTION

[0002] U.S. Pat. No. 5,718,741 (Hull et al.), which is assigned to theassignee of this application, the disclosure of which is incorporatedherein by reference, discloses a forehearth for cooling a stream ofmolten glass as it flows from a glass melting furnace to a formingmachine for forming the molten glass into finished products, forexample, hollow glass containers of the type widely used in packagingvarious food, beverage and other products. In the arrangement of the'741 Patent, and in a variety of other types of forehearths, moltenglass flows downwardly through an opening, or a plurality of openings,in the bottom of a feeder bowl at an end of the forehearth that isremote from the end into which molten glass from the melting furnaceflows.

[0003] To control the flow of molten glass from a forehearth feederbowl, a vertically extending, refractory feeder tube is provided withits lowermost end immersed in the feeder bowl to a level slightly abovethe inside surface of the bottom of the feeder bowl and surrounding theopening(s) at the bottom of the feeder bowl, and the ceramic tube iscaused to rotate slowly during the operation of the forehearth to ensurea proper mixing and temperature uniformity of the molten glass flowingfrom the feeder bowl. A feeder bowl refractory tube with a tube drivesystem of this general type is disclosed in U.S. Pat. No. 5,660,610(DiFrank), which is also assigned to the assignee of this application,the disclosure of which is also incorporated by reference herein. Otherglass forehearth feeder bowl feeder tube arrangements are described inU.S. Pat. No. 5,693,114 (Scott), U.S. Pat. No. 4,514,209 (Mumford) andU.S. Pat. No. 4,478,631 (Mumford), the disclosure of each of which isalso incorporated by reference herein.

[0004] From time to time during the operation of a glass manufacturingsystem of a type employing a forehearth feeder bowl feeder tube of thetype described above it is necessary to remove the feeder tube and/orthe feeder bowl for repair or replacement. In the case of thereplacement of the feeder bowl, the feeder tube must also be swunghorizontally out of the way of the feeder bowl as well as being liftedvertically so that its lower edge clears the upper extent of the feederbowl. It is also necessary from time to time to be able to adjust theheight of the feeder tube. As a feeder tube of this type is quitemassive, very large forces are required to lift it from its operatingposition. Heretofore, counterweighted lift mechanisms were employed forthis purpose, and these mechanisms typically employed gear boxes withconsiderable backlash, thus making precise positioning and motions ofthe feeder tube very difficult. Moreover, in these arrangements, preciseadjustment of the position of the feeder tube in a horizontal plane, inX and/or Y directions, was difficult to achieve in that the horizontalmotions of the counterweight lift mechanisms could not be isolated alongX or Y axes. Further, counterweighted lift mechanisms are cumbersomebecause of the dead weights employed in them, and the vertical feedertube slide supports are subject to wear during up and down tubeadjustments, which can impart a wobbling motion to the tube supportsystem and thereby lead to undesired glass gob weight variation in afeeder bowl used in conjunction with a glass container forming machineof the individual section (I.S.) type. Also, from time to time, it isnecessary to replace a feeder bowl itself. In the prior art, thisrequired removal of the entire feeder tube mechanism itself.

BRIEF DESCRIPTION OF THE INVENTION

[0005] According to the present invention, the aforesaid and otherproblems associated with prior art glass forehearth feeder bowl feedertube lift systems are avoided by a feeder tube lift system that employsa single, multiple shaft, servo motor operated, ball screw liftmechanism of sufficient capacity to sustain a cantilevered feeder tubesupport mechanism with minimal deflection. Such a lift mechanisminvolves no, or very little, backlash in its motions, thereby permittingprecise control of the elevation of the lift tube in the feeder bowl,which is important in achieving accurate control of glass gob weight inan I.S. machine glass container manufacturing operation. The feeder tubelift mechanism of the present invention is also capable of true isolatedadjustments in a horizontal plane, both along X and Y axes, and it canbe moved without slide wear, thereby avoiding introduction of wobblingmotion to the tube support system. The servo motor powered ball screwlift mechanism of the present invention is lubricated by a lubricantthat is recirculated with a closed system to ensure long life forbearings of the mechanism and the ball roller nut, and avoidinglubricant leakage and the need for lubricant replacement.

[0006] Accordingly, it is an object of the present invention to providean improved lift mechanism for a feeder tube of a type employed in aglass forehearth feeder bowl. More particularly, it is an object of thepresent invention to provide a lift mechanism of the foregoing type thatis not counterweighted, and thereby avoids the problems associated withthe prior art, of counterweighted feeder tube lift mechanisms.

[0007] For further understanding of the present invention and theobjects thereof, attention is directed to the drawing and the followingbrief description thereof, to the detailed description of the preferredembodiment and to the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

[0008]FIG. 1 is a fragmentary elevational view of a feeder tube assemblyaccording to the preferred embodiment of the present invention;

[0009]FIG. 2 is a plan view of the feeder tube assembly of FIG. 1;

[0010]FIG. 3 is a sectional view taken on line 3-3 of FIG. 2;

[0011]FIG. 4 is a fragmentary view, at an enlarged scale, of a portionof the feeder tube assembly shown in FIG. 1;

[0012]FIG. 5 is a fragmentary sectional view taken on line 5-5 of FIG.2;

[0013]FIG. 6 is a sectional view taken on line 6-6 of FIG. 5;

[0014]FIG. 7 is a fragmentary perspective view of a portion of thefeeder tube assembly of FIGS. 1-6;

[0015]FIG. 8 is a fragmentary elevational view, partly in cross section,of a portion of the feeder tube assembly of FIGS. 1-6;

[0016]FIG. 9 is a view similar to FIG. 8 at a right angle thereto;

[0017]FIG. 10 is a plan view of an element of the feeder tube assemblyof FIGS. 1-6;

[0018]FIG. 11 is a sectional view taken online 11-11 of FIG. 10; and

[0019]FIG. 12 is an exploded, perspective view of a portion of theapparatus illustrated in FIGS. 8 and 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] A feeder tube assembly according to the preferred embodiment ofthe present invention is identified generally by reference numeral 20 inthe drawing. The feeder tube assembly 20 includes a refractory feedertube 22 which, as is shown in FIG. 3, is adapted to be inserted into amolten glass feeder bowl B at the outlet end of a generally horizontallyextending molten glass cooling forehearth, otherwise not shown, whichmay be of conventional construction. The feeder tube 22 is verticallyoriented in the feeder tube assembly, and its lowermost end ispositioned slightly above the inside surface of the feeder bowl B, tothereby allow molten glass to flow through the space below the feedertube 22 to exit through openings O at the bottom of the feeder bowl B.

[0021] The feeder tube 22 has an outwardly projecting flange 24 at itsupper end, and the flange 24 is clamped in a clamping ring subassembly86, which is provided with lifting eyes 18 and serves to support thefeeder tube 22 on an inwardly projecting flange 26 of a rotatable ringsubassembly 28. The rotatable ring subassembly 28 is cantilevered at theend of a support arm 30, and the subassembly 28 includes an upwardlyfacing ring gear 32, and is caused to rotate slowly with respect to thesupport arm 30 by the engagement of the ring gear 32 by a driven pinion34 at an end of a driven rod 36, which is driven by a motor 38 actingthrough a speed reducer 40, all of which are supported on the supportarm 32 at an end opposed to the end on which the feeder tube 22 issuspended. The rotation of the feeder tube 22 helps to properly mix themolten glass in the feeder bowl B to thereby ensure proper homogeneityand temperature uniformity of the molten glass exiting through theopenings O.

[0022] The support arm 30 is supported along a vertically extending axisA that extends through a handle 42, which serves to lock the support armin a non-adjustable and a non-pivotable position as will be hereinafterdescribed more fully. The support arm 30 is also adjustably supportedfor precisely controllable motion along the axis A on a verticallyextending servo motor powered precision linear actuator 44, a cylinderportion 44 a of which is secured to the framework 46 of the feeder tubeassembly 20. The linear actuator 44 is of a type that is available fromE-Drive Design, Inc. of Glastonbury, CT under the product designationModel EA2S-7.312-L/D-1836, and will be subsequently described in greaterdetail. The support arm 30 has an opening 48 extending therethroughconcentric with the axis A and generally concentric with thelongitudinal central axis of the linear actuator 44. A spaced apartplurality of rods 50 extend outwardly and upwardly from the linearactuator 44 and are caused to reciprocate in unison along vertical axesby the actuation of the linear actuator 44. The rods 50 arenon-rotatably received in a block 52 of a composite adjustment mechanism54, which is supported on an inverted cup-shaped structure 56 that issecured to the upper surface of the support arm 30.

[0023] The adjustment mechanism 54 includes an upper plate 58, and thesupport arm 30 is moveable relative to the upper plate 58 along opposedspaced apart slot 60 in the structure 56, which extend generallyparallel to the longitudinal axis of the support arm 30 to provide forprecisely controllable adjustment of the support arm 30, and thereby ofthe feeder tube 22, in the X direction. To accomplish such adjustment,an adjusting screw 62, which is threadably received in the structure 56,has an inner end that engages the upper plate 58, and the turning of theadjustment screw 62 is effective to move the support arm 30 to or fro inthe X direction relative to the adjustment mechanism 54, whose positionin an horizontal plane is fixed by virtue of the attachment of thelinear actuator 44 to the framework 46, as described.

[0024] The adjustment mechanism 54 also includes a lower plate 64, andthe support arm 30 is moveable relative to the lower plate 64 alongopposed, spaced apart slots 66 in the cup-shaped structure 56, whichextend transversely of the longitudinal axis of the support arm 30, toprovide for precisely controllable adjustment of the support arm 30, andthereby of the feeder tube 22, in the Y direction. To accomplish suchadjustment, an adjustment screw 68, which is threadably received in anextension of the upper plate 58, has an inner end that engages a bossportion 70 of the cup-shaped structure 56, and turning of the adjustmentscrew 68 moves the support arm to or fro in the Y direction relative tothe adjustment mechanism 54. Of course, when the handle 42 is tighteneddown against the boss 70, the support arm 30 will be frictionallyprevented from moving relative to the adjustment mechanism 54, either inthe X direction or the Y direction.

[0025] Because of the high temperature environment in which the feedertube 22 is used, it is important to cool the end of the support arm 30from which the feeder tube 22 is suspended. To that end, an annularpassage 72 is provided in the support arm 30 surrounding and extendinggenerally concentrically of the feeder tube 22, and cooling air or othercooling fluid is caused to flow through the passage 72 from inlet andoutlet lines 74, 76, respectively. Further, a generally semi-cylindricalheat shield 78 is suspended form the support arm 30 at a location partlysurrounding the upper end of the linear actuator 44, and between thelinear actuator 44 and the feeder tube 22, to retard heating of thelinear actuator 44 by heat radiated from the feeder bowl B.

[0026] The flange 24 of the feeder tube 22 is securely, but releasably,held in engagement with the flange 26 by a plurality ofcircumferentially spaced apart latch mechanisms, each generallyidentified by reference numeral 80, three such latch mechanisms beingshown in FIG. 2. Each latch mechanism 80 comprises a lever 82 with ahandle portion 82 a at an end thereof and an enlarged cam portion 82 bat an opposed end. The lever 82 is pivotably connected to a supportmember 84 about an axis C and, when the lever extends vertically, thecam portion 82 b securely engages and upper surface of the clamping ring86 which engages the flange 24 of the feeder tube 22 to forcibly pressthe flange 24 into its desired operating position. When the lever 82 ispivoted to a horizontal orientation, the cam portion 82 b no longerengages the ring 86. In this position, the feeder tube 22 may be removedfrom the feeder bowl B by a simple lifting motion, using the liftingeyes 18 each of the latch mechanisms 80 being moveable out of alignmentwith the feeder tube 22 by pivotably connecting the support member 84 toa fixed structure 88 about an axis D. Before installing a new feedertube 20, the support arm 30 should be elevated so that the new feedertube 20 does not contact the feeder bowl B.

[0027] The pivoting of the support arm 30 about the axis A is done whenit is desired to replace a feeder bowl B. After releasing the feedertube 22 from its engaged position by the release of the latch mechanisms80, as heretofore described, and after the actuation of the linearactuator 44 to lift the support arm 30 to an elevation such that thebottom of the feeder tube 22 is free of the feeder bowl B, the feedertube 22 is then hoisted from the subassembly 28. To this end, the upperplate 58 of the adjustment mechanism 54 is pivotable with respect to thelower plate 64, after removal of an alignment pin 114 thatcircumferencially aligns the upper plate 58, the lower plate 64 and theblock 52 with respect to one another during the operation of the feedertube assembly 20.

[0028] The linear actuator 44 is powered by an a.c. servo motor 90,which is co-axially connected to the actuator 44, though it iscontemplated that the connection can be by way of parallel axes with aV-belt or other drive extending therebetween. In any case, an assemblyincluding the actuator 44 and the servo motor 90 is available fromE-Drive Design of Glastonbury, Conn., as heretofore described. As isshown in FIG. 8, the motor 90 has a hollow output shaft 92. The hollowoutput shaft of the motor 90 is slipped onto an input shaft 94 of thelinear actuator 44 (FIGS. 8 and 11), which has an internal ball screwdrive 96. The ball screw drive 96 translates rotary motion of the shaft92 into linear motion of an annular member 98, either to or frodepending on the direction of rotation of the shaft 92.

[0029] The annular member 98 may be manually positioned by turning alever 102, which is fixed to the shaft 92. The shaft 92 extends to alevel below the motor 90, actually below the level of an arcuate heatshield 100 that protects the motor 90 from thermal radiation from thefeeder bowl B, and the lever 102 extends outwardly from the shaft 92.The lever 102 has a handle 104 projecting downwardly therefrom, at alocation radially outwardly of the shaft 92, and the shaft 92 may beturned by manually engaging the handle 104 and using it to turn thelever 102.

[0030] The motor 90 is provided with an annular brake 106 that rotateswith the shaft 92, and the brake 106 is selectively engageable by adouble-ended constricting band 108. The band 108, when in itsnon-constricting mode, does not engage the brake 106 and provides nobraking effect in such mode. However, the band 108 can be selectivelytightened by the actuation of a pneumatic cylinder 110 acting through alinkage system 112, and, when the cylinder 110 is extended, as shown inFIG. 12, the band 108 will be constricted to engage the brake 106, thusretarding turning action of the shaft 92, 94 and thereby locking theplatform 30 in a desired elevation.

[0031] The linear actuator 44 requires constant lubrication in service,and to that end a plurality of lubricating oil inlet lines 116, 118,120, 122, 124, 126 and 128 (FIG. 4) to deliver lubricating oil from acommon source (not shown) to various locations of the linear actuator44. These locations include inlets 130, 132 (FIG. 11) of the cylinder 44a of the linear actuator 44 and each of the four (4) rods 50 (FIG. 6)that extend therefrom. The lubricating oil is collected at the bottom ofthe cylinder 44 a and returned to the source for recycling, by way of areturn line 134 (FIG. 4) preferably after being filtered and cooled ifnecessary, with a supply of fresh, make-up oil being provided to make upfor any oil losses in the system. The lubricating system, as described,is a closed system that provides adequate lubrication for all movingsurfaces while simultaneously minimizing lubricant losses in a hot andrelatively inaccessible environment and serving to conserve a producederived from expensive and irreplaceable natural resources.

[0032] Although the best mode contemplated by the inventors' forcarrying out the present invention as of the filing date hereof has beenshown and described herein, it will be apparent to those skilled in theart that suitable modifications, variations, and equivalents may be madewithout departing from the scope of the invention, such scope beinglimited solely by the terms of the following claims and the legalequivalents thereof.

What is claimed is:
 1. A feeder tube assembly for a feeder bowl of aglass melting furnace forehearth, said feeder tube assembly comprising:a generally horizontally extending elongate support arm having anopposed pair of ends; a generally vertically extending feeder tube;means carried by said support arm for releasably securing said feedertube to said support arm at a location adjacent an end of said supportarm; a generally vertically extending servo motor actuated linearactuator supporting said support arm at a location between said opposedends, said servo motor actuated linear actuator being operable to adjustthe elevation of said support arm.
 2. A feeder tube assembly accordingto claim 1 and further comprising; means carried by said support arm forrotating said feeder tube relative to said support arm about alongitudinal central axis of said feeder tube.
 3. A feeder tube assemblyaccording to claim 1 wherein; said support arm has an opening positionedbetween its opposed ends, said opening being vertically aligned with alongitudinal central axis of said linear actuator, said support armbeing rotatable with respect to said linear actuator about saidlongitudinal central axis of said linear actuator.
 4. A feeder tubeassembly according to claim 3 and further comprising; means foradjusting the position of said support arm relative to said linearactuator along an axis extending longitudinally of said support arm. 5.A feeder tube assembly according to claim 4 and further comprising;means for adjusting the position of said support arm relative to saidlinear actuator along an axis extending transversely of said supportarm.
 6. A feeder tube assembly according to claim 1 wherein; saidgenerally vertically extending servo motor actuated linear actuatorcomprises a ball screw mechanism for translating rotary motion of anoutput shaft of said servo motor to linear motion.
 7. A feeder tubeassembly according to claim 6 wherein; said generally verticallyextending servo motor actuated linear actuator further comprises meansfor releasably braking said servo motor against rotation.
 8. A feedertube assembly according to claim 1 wherein said support arm has a secondopening, said second opening of said support arm being verticallyaligned with said feeder tube, and further comprising; means for coolingsaid support arm in an annular pattern at a location adjacent saidsecond opening.
 9. A feeder tube assembly according to claim 6 whereinsaid linear actuator has a housing and a member at least partlycontained within said housing and being moveable with respect to saidhousing between first and second positions as a result of rotary motionof said output shaft of said servo motor, and further comprising; afixed support structure, said housing being fixedly secured to saidfixed support structure.
 10. A feeder tube assembly according to claim 9wherein said linear actuator further comprises; a block; a space apartplurality of rods extending from said member of said linear actuator tosaid block; and means for tightening said support arm relative to saidblock for preventing rotation of said support arm relative to saidlinear actuator.
 11. A feeder tube assembly according to claim 9 whereinsaid linear actuator has an input shaft, said input shaft of said linearactuator being integral with said output shaft of said servo motor, andfurther comprising; means for turning said input shaft of said linearactuator and said output shaft of said servo motor independently ofoperation of said servo motor.
 12. A feeder tube assembly according toclaim 2 wherein said means for rotating said feeder tube comprises; aring gear assembly generally concentrically positioned with respect tosaid feeder tube, said ring gear being non rotatable with respect tosaid feeder tube; a pinion gear engaging said ring gear; and means forimparting rotary motion to said pinion gear.
 13. A feeder tube assemblyaccording to claim 1 and further comprising: closed lubricating oilcirculating means for continuously lubricating said servo motor actuatedlinear actuator.
 14. The method of replacing a feeder bowl of a glassmelting furnace forehearth installation, the feeder bowl having aninstalled position in the installation, the installation having a feedertube assembly with a generally horizontally extending elongate supportarm and a feeder tube rotatably secured to an end of the support arm andnormally positioned with a lowermost end immersed in the feeder bowl,the method comprising: lifting the support arm until the lowermost endof the feeder tube is above the feeder bowl; pivoting the support armabout an axis spaced from the feeder tube until the feeder tube is nolonger in vertical alignment with the feeder bowl; and then lifting thefeeder bowl from its installed position without otherwise removing thesupport arm.